As a stereoscopic shooting apparatus for stereo imaging, a pair of image shooting devices fixed to a single frame has been well known. In this stereoscopic shooting apparatus, one image shooting device shoots an image for the left eye while the other shoots an image for the right eye. These left-eye and right-eye images are combined to obtain a stereo image.
There is another stereoscopic shooting apparatus that can produce a stereo image using only one image shooting device. In this stereoscopic shooting apparatus, the image shooting device shoots a left-eye image first, then shoots a right-eye image after shifting itself to the right-eye position, and combine the left-eye image and the right-eye image being currently taken to create a stereo image. Since the right-eye image is taken while adjusting the position of the right-eye image relative to the left-eye image, an improved stereoscopic effect can be obtained.
However, both of the above stereoscopic shooting apparatuses are awkward to use. Thus, efforts have been made of find a simple technique in which a stereo image is produced by enabling two operators to operate the two image shooting devices separately and shoot a subject at the same time. As an example of a camera system based on such a technique, there is a disclosure in JP2010-157850A (Patent Document 1).
The camera system described in Patent Document 1 includes the first and second cameras that can communicate with each other. The first camera includes: an image shooting unit that shoots subjects to acquire the first image; a communication unit for receiving the second image of subjects shot by the second camera; an image processing unit that separately recognizes a main subject from the first and second images and creates composition information including the main subject and the background; a determination unit that, by comparing the composition information of the first image and the composition information of the second image, determines whether a stereo image can be formed from the first and second images; and, a display unit for displaying the popropriety of stereo imaging. The determination unit determines that stereo imaging is impossible if the size of the main subject in the first image is different from the size of the main subject in the second image. Herein, the condition in which the main subject in the first image and that in the second image are equal in size, means that the angular field of the first image coincides with the angular field of the second image.